Profiled clamping jaw for clamping workpieces

ABSTRACT

A profiled clamping jaw for a clamping device has a base body (12) and a clamping surface (14) arranged on the base body and adaptable to the surface profile of a workpiece (54). To make it possible to adapt by simple means the clamping surface (14) of the profiled clamping jaw (10) to the surface profile of the workpiece, the claiming surface (14) is composed of a plurality of pressure pieces (16) movable with respect to the base body (12) and capable of being locked thereon in a determined clamping position.

DESCRIPTION

The invention relates to a profiled clamping jaw for a clamping devicecomprising a base body and a clamping surface arranged on the base bodyand adapted to the surface contour of a workpiece, and a process forclamping of workpieces by means of a profiled clamping jaw of the abovetype.

Clamping jaws are parts of clamping devices, as they, for example, areneeded in vises, machine tools or machining centers for holding ofworkpieces. To clamp profiled rods in particular for the window, door orfacade-wall construction, profiled clamping jaws have been used up tonow which, in their surface contour, are adapted to the contour of theworkpiece to be clamped. Thus, a special profiled clamping jaw iscreated for each workpiece type, which jaw must be exchanged in the caseof a change of the workpiece to be worked in the respective clampingdevice. The known profiled clamping jaws can therefore because of thelong change-over times only be economically utilized in the seriesproduction for medium or larger lots of at least 200 pieces, not,however, in the individual or small-series production. This isparticularly true for use in large series boring and milling machines,in which a plurality of clamping devices with profiled clamping jaws arebeing utilized.

Based on this, the basic purpose of the invention is to develop aprofiled clamping jaw and a process for clamping of workpieces, withwhich in a simple manner an adapting to different workpiece contours ispossible.

To attain this purpose the characteristic combinations disclosed inclaims 1 or 20 are suggested. Further advantageous developments andfurther embodiments of the invention result from the dependent claims.

The basic principle of the inventive solution is that the clampingsurface can be shaped by moving the base body toward the workpiece untilreaching a clamping position and can thereby be automatically adapted tothe contour of the workpiece surface. This principle can advantageouslybe realized such that the clamping surface is composed of a plurality ofpressure pieces which are movable relative to the base bodyindependently from one another and can be locked on same in a clampingposition. The pressure pieces are thereby advantageously movable backand forth in clamping direction of the profiled clamping jaw on the basebody and can be locked together on the base body.

An advantageous development of the invention provides that the pressurepieces are movable against the force of a spring in direction of thebase body so that they can be moved against the spring force indirection of the base body during movement of the base body toward theworkpiece to be clamped under the action of the workpiece surface andcan be locked in the clamping position.

A further advantageous development of the invention provides that eachpressure piece is guided with a clamping ram in a sliding guide of thebase body. The path of movement of the clamping ram is defined inclamping direction advantageously by a front end stop defining theinitial position of the pressure pieces and can be locked in everyposition by means of a blocking member on the base body. The blockingmembers of the clamping rams can thereby be operated advantageouslytogether mechanically, pneumatically or hydraulically. To operate theblocking members, switching members are advantageously provided which,during movement of the clamping rams, can be advantageously released inthe vicinity of their rearward end position.

The blocking members are constructed, for example, as a forming orexpanding element which can be operated through a pressure pistonmovable relative to the clamping ram and can be clamped between theclamping ram and a cylinder wall of the base body, and are thereby inparticular constructed as a clamping sleeve, an annular clamping disk orannular forming spring. It is basically also possible to design theblocking members as a clamping block arranged between the base body andclamping ram.

In order to avoid damage to the workpiece surface, the pressure piecescan consist of an elastomer material or can have a coating of anelastomer material. A further improvement in this respect can beachieved such that the pressure pieces are coated on the front side witha closed diaphragm of a rubber-elastic material, which diaphragm formsthe clamping surface. Thus, a closed clamping surface is obtained withwhich a contamination of the space between the pressure pieces can beavoided.

A further preferred development of the invention provides that theclamping rams each carry a ram piston engaging a ram cylinder of thebase body, and that the ram cylinders can be loaded with hydraulic fluidin clamping direction through a common hydraulic distributor. The rampistons are thereby loaded with atmospheric pressure from thesurrounding air on their piston surface opposite the hydraulicdistributor. Each ram piston can be loaded with the hydraulic fluidthrough a hydraulically operable check valve arranged between thehydraulic distributor and the associated ram cylinder. The check valveshaving the function of the blocking member have for this purposeadvantageously a control piston arranged in a control cylinder andloadable on two sides with hydraulic fluid. The one piston surface ofthe control pistons, which surface is advantageously on the side of thecheck valve, and the ram pistons are thereby advantageously loaded withhydraulic fluid from the same hydraulic distributor.

According to a preferred development of the invention, the associatedram cylinders and the control cylinders are aligned coaxially with oneanother so that the check valves are operated through their controlpistons axially with respect to the ram cylinders.

A further preferred development provides that the hydrocylinders arearranged in a common cylinder block, whereas the check valves arearranged in a common valve plate which is connected, preferably screwed,to the common cylinder block. The control cylinders can in turn bearranged in a common cylinder plate, which is connected, preferablyscrewed, to the valve plate, and which is closed by a base plate on theside opposite the valve plate. In this manner it is possible with simplestructural means to construct the hydraulic distributor through a freespace arranged between the valve plate and the cylinder plate, whereasbetween the valve plate and the base plate there can be provided inaddition a second hydraulic distributor as a free space, which secondhydraulic distributor communicates with the control cylinder. A coverplate closing off the cylinder block and having openings forming thesliding guide for penetration by the clamping rams can be provided onthe side opposite the base plate, with a free space being able to besaved between the cover plate and the cylinder block, which free spaceis connected to the ram cylinders and preferably communicates with theatmosphere.

The profiled clamping jaws of the invention are with a particularadvantage inserted into the clamping devices which have a block carriagemovable on a machine frame in clamping direction toward a block stopadjustable preferably through a center control in accordance with thesize of a workpiece to be clamped, and a shaping and clamping carriagemovable in clamping direction on the block carriage and carrying theprofiled clamping jaw. The profiled clamping jaw of the invention canbasically also be used in a common vise. The base body of the profiledclamping jaw must in this case be merely fastened on the clamping jaw ofthe vise.

Workpieces can be clamped with the profiled clamping jaw of theinvention in such a manner that first the base body is moved toward theworkpiece and the clamping surface is thereby shaped with an automaticadaptation to the contour of the workpiece surface, and that theclamping surface after reaching a clamping position relative to the basebody is set nonshapably and is pressed with the workpiece being clampedwith a pregiven holding force against its surface. Thus, it is achievedthat workpieces with essentially any desired, also complicated surfacecontours, can be gripped force-lockingly and form-lockingly at a fullyautomatic handling with an automatic tolerance balance with alarge-surface bearing.

The invention will be discussed in greater detail hereinafter inconnection with the exemplary embodiments schematically illustrated inthe drawings, in which:

FIG. 1 shows a section out of a clamping device with four crosswisearranged profiled clamping jaws;

FIG. 2 is a cross-sectional view taken along the section line 2--2 ofFIG. 1;

FIG. 3 is a side view of a vise having profiled clamping jaws;

FIG. 4 is a top view of the vise according to FIG. 3;

FIG. 5 is a longitudinal cross-sectional view of a profiled clamping jawin an enlarged illustration compared with FIGS. 1 to 4;

FIG. 6 is a top view of a profiled clamping jaw with hydraulicallyoperable clamping rams;

FIG. 7 is a partially cross-sectional side view of the profiled clampingjaw according to FIG. 6;

FIG. 8 shows a section of FIG. 7 in an enlarged illustration.

The profiled clamping jaws 10 illustrated in the drawings consistessentially of a base body 12 and a clamping surface 14 composed of aplurality of pressure pieces of an elastomer material, which pressurepieces are movable independently from one another relative to the basebody 12 along a lifting path h. The pressure pieces 16 are each arrangedon one end of a clamping ram 18 which is movably supported in liftingdirection in a sliding guide 20 of the base body 12.

In the case of FIG. 5, the clamping rams 18 each extend within the basebody 12 through a cylindrical recess 22 and are there loaded by apressure spring 28 with a force directed in the direction of the arrow30, which pressure spring 28 is clamped between the cylinder base 24 andan adjusting ring 26 fastened on the clamping ram 18 and having a flange25. The pressure pieces 16 thus assume in their clamped-in rest positionthe initial position 16' shown by dash-dotted lines in FIG. 5, in whichposition 16' the clamping ram 18 rests with its adjusting ring 26 underthe action of the pressure spring 28 against the end stop 32. Theclamping rams 18 extend within the base body 12 furthermore through ablocking member 34 which, in the exemplary embodiment illustrated inFIG. 5, includes a cylinder chamber 36 arranged in the base body 16 andthrough which extends the clamping ram 18, and two forming elements 38arranged in the cylinder chamber 36 and are designed, for example, asannular clamping disks or annular forming springs, and an annular piston40 surrounding the clamping ram 18. The forming elements 38 of theblocking member 34 can be moved, in every position of the clamping ram18, into their blocking position supported both on the inside wall ofthe cylinder chamber 36 and also on the ram surface and when the annularpiston 40 is located with pressurized hydraulic or pneumatic mediathrough the connecting piece 42 and the bottom side of the annularchamber 44. The piece 42 is connected to the annular chambers 44 of allblocking members 34 so that the blocking of all clamping rams 18 withinthe base body 12 occurs at the same time. An auxiliary spring 46arranged within the annular chamber 44 takes care that the two-partannular piston 40 is, even in the relaxed state, always in a definedinitial position, whereas the sealing rings 48 seal off the base bodyagainst overflowing and escaping pressurized fluid. The blocking membersare operated by switching members 52 which can be released in theirrearward end position through the clamping rams 18.

FIG. 5 shows that the base body 12 is composed of several disk-shapedstructural parts which are connected through several clamping-screwpairs 50 distributed over the circumference.

The clamping rams 18 of the profiled clamping jaws shown in FIGS. 6 to 8are moved with their pressure pieces 16 hydraulically into their initialposition shown in FIG. 7 and are locked in their clamping position witha hydraulically operable check valve 70. The rams 18 engage for thispurpose with a ram piston 72 arranged at their rearward end in a ramcylinder 74 within the base body 12, which cylinder 74 can be loaded atthe bottom side through a hydraulic distributor 76 and the valve opening80 defined by the conical seat 78 of the check valve 70, with hydraulicfluid. The ram cylinders 74 communicate at their rod-side end through adistributor chamber 82 and the opening 84 with the surrounding air. Thevalve needle 84 of the check valve 70 is operated through a controlpiston 90 guided in a control cylinder 86 and is loadable on both sideswith hydraulic fluid out of the distributor chambers 76 and 88. As canparticularly be seen in FIG. 8, the base body 12 is also in this casecomposed of several blocklike or disklike structural parts which areconnected by several circumferentially arranged clamping screws 50. Theclamping cylinders 74 are thereby provided in a common cylinder block92, which is closed off on the side of the rods by a cover plate 94containing the sliding guides 20 for the rams 18 and an intermediateplate 96 containing the connection 84 and the distributor chamber 82. Adistributor plate 98 with the valve seats 78, the valve openings 80 anda hydraulic connection 100 leading to the distributor chamber 74 isprovided on the bottom broad side surface of the cylinder block 92. Acylinder plate 102 with the control cylinders 86 is provided on the sideof the valve plate 98, which side is opposite the cylinder block, forreceiving the control pistons 90 which are additionally provided withfront-side recesses for forming the hydraulic distributors 76, 88 and aconnection 104 leading to the hydraulic distributor 88. The plate 102 isclosed off on the outside by a base plate 106.

The hydraulic profiled clamping jaw according to FIGS. 6 to 8 operatesas follows: In order to drive the clamping ram 18 out into its initialposition shown in FIG. 7, the distributor chamber 76 is loaded withpressurized oil through the connection 100, while the distributorchamber 88 is connected to the tank. The control pistons 90 are in thismanner moved with the valve needles 84 from their blocking positionshown in FIG. 8 into the open position according to FIG. 7. Pressurizedoil moves in this position out of the distributor chamber 76 into theram cylinders 74 and drives the ram 18 into its initial position shownin FIG. 7. The profiled clamping jaw 10 is during a clamping operationmoved with its pressure pieces 16 against a surface to be clamped, withthe distributor chamber 76, when the valves 70 are open, being opentoward the tank or toward an elastic pressure storage such thathydraulic fluid can be removed from the clamping cylinders 74. Afterreaching the clamping position, the distributor chamber 88 is loadedwith pressure oil through the connection 104 and the valves 70 are thusmoved into their blocking position. In order to avoid leakage out of theclamping cylinders, it is also possible to maintain a certain hydraulicpressure in the distributor chamber 76.

In the exemplary embodiment of a clamping device, sections of which arein FIGS. 1 and 2, there exist four profiled clamping jaws 10, betweenthe clamping surfaces 14 of which is clamped a workpiece 54 with acomplicated surface contour, which workpiece is designed as a profiledrail. The clamping surface 14 is adapted to the surface contour suchthat the base bodies 12 are moved initially with nonclamped clampingrams 18 toward the respective surface part until they strike thepressure pieces 16 which are in their initial position. The nonclampedclamping rams 18 are then during the course of a further movement movedunder the action of the workpiece surface against the force of thepressure springs 28 into the base body until the clamping ram, which hasbeen moved the farthest, releases through the associated shifting member52 the blocking of the clamping ram 18 within the base body 12 in theabove-described manner. By suitably adapting the lift h to thedimensions of the projecting parts 56 of the workpiece, all pressurepieces 16 rest in this case correctly with respect to the contour on theworkpiece surface so that the holding forces engaging the workpiece aredistributed over the entire clamping surface 14 of the profiled clampingjaws. The clamping of the workpieces between the profiled clamping jawsincluding the adapting of the claiming surface 14 to the surface contourcan occur fully automatically in suitable clamping devices.

It is possible as this can be seen in FIGS. 3 and 4 to arrange thedescribed profiled clamping jaws also on a manually operated vise 60.The base bodies 12 of the profiled clamping jaws 10 must for thispurpose be merely fastened, preferably screwed to the clamping jaw 58 ofthe vise 60. The workpiece 54 is then clamped with an adaptation to theworkpiece surface in the above-described manner with the one differencethat the vise 60 with the profiled clamping jaw 10 through the crankpin62 and the blocking of the clamping ram 18 after adaptation of theclamping surface 14 to the surface contour is each done manually.

In summary the following is to be stated: The invention relates to aprofiled clamping jaw for a clamping device with a base body 12 and aclamping surface 14 arranged on the base body and adaptable to thesurface contour of a workpiece 54. In order to enable with simple meansan adaptation of the clamping surface 14 of the profiled clamping jaw 10to the surface contour of the workpiece 54, the clamping surface 14 iscomposed of a plurality of pressure pieces which are movable relative tothe base body 12 and which can be locked in a clamping position on saidbase body.

We claim:
 1. In a profiled clamping jaw for a clamping device comprising a base body and a shapable clamping surface arranged on said base body, said clamping surface being shapable by moving said base body toward a workpiece until a clamping position is reached, and thereby automatically adapting to the contour of the workpiece surface, said clamping surface being composed of a plurality of pressure pieces each movable independently of one another relative to said base body and being lockable in said clamping position on said base body, each said pressure piece being guided by a clamping ram in a sliding guide of said base body, said clamping rams each carrying a ram piston in a ram cylinder of said base body, and said ram cylinders being loadable through a common hydraulic distributor in said clamping direction with hydraulic fluid, the improvement wherein between individual said ram cylinders and said hydraulic distributor there is arranged a check valve, wherein said check valves each carry a single control piston having a plurality of piston surfaces loadable on two sides with hydraulic fluid and arranged in a control cylinder, of said base body and wherein said control pistons are loadable together with hydraulic fluid on their piston surfaces, which are opposite to one another, through two separate hydraulic distributors.
 2. The profiled clamping jaw according to claim 1, wherein said ram pistons are loaded with atmospheric pressure at their piston surface opposite said hydraulic distributor.
 3. The profiled clamping jaw according to claim 1, wherein said ram pistons and said piston surfaces of said control pistons are loadable with hydraulic fluid from a same hydraulic distributor.
 4. The profiled clamping jaw according to claim 1, wherein said ram cylinders and said control cylinders, which are associated with one another, are aligned axially parallel.
 5. In a profiled clamping jaw for a clamping device comprising a base body and a shapable clamping surface arranged on said base body, said clamping surface being shapable by moving said base body toward a workpiece until a clamping position is reached and thereby automatically adapting to the contour of the workpiece surface, said clamping surface being composed of a plurality of pressure pieces each movable independently of one another relative to said base body and being lockable in said clamping position on said base body, each said pressure piece being guided by a clamping ram in a sliding guide of said base body, said clamping rams each carrying a ram piston in a ram cylinder of said base body, and said ram cylinders being loadable with hydraulic fluid in said clamping direction through a common hydraulic distributor, the improvement wherein between each of the individual said ram cylinders and said hydraulic distributor there is arranged a check valve, wherein said check valves each carry a single control piston having a plurality of piston surfaces arranged in a control cylinder and loadable with hydraulic fluid on two sides, and wherein said ram pistons and said piston surfaces of said control pistons, which said piston surfaces are on the side of said check valve, are loadable with hydraulic fluid from a same said hydraulic distributor.
 6. The profiled clamping jaw according to claim 5, wherein said ram cylinders and said control cylinders, which are associated with one another, are aligned axially parallel.
 7. The profiled clamping jaw according to claim 6, wherein said ram cylinders are arranged in a common cylinder block.
 8. The profiled clamping jaw according to claim 7, wherein said check valves are arranged in a common valve plate, which is connected to said cylinder block.
 9. The profiled clamping jaw according to claim 8, wherein said control cylinders are arranged in a single common cylinder plate connected to said valve plate, and said control cylinders are closed off on a side opposite said valve plate by a base plate.
 10. The profiled clamping jaw according to claim 9, wherein between said valve plate and said cylinder plate there is arranged a free space forming said hydraulic distributor.
 11. The profiled clamping jaw according to claim 8, including a free space arranged between said valve plate and a base plate forming a second hydraulic distributor communicating with said control cylinders.
 12. The profiled clamping jaw according to claim 5, including a cover plate closing off a cylinder block on a side of said pressure piece and having a plurality of openings for passage of said clamping rams.
 13. The profiled clamping jaw according to claim 11, wherein between said base plate and said cylinder block there is arranged a space connected to said ram cylinders on a side of a rod portion of said ram piston and communicating with the atmosphere. 